With continuous development and improvement of communications technologies, operators use optical node splitting in a hybrid fiber-coax (HFC) network, to improve a household average access rate of users. Using the data over cable service interface specification (DOCSIS), the HFC network supports a computer network and a cable television network, and implements transmission of an Internet Protocol (IP) data packet between a transmit device and a cable modem (CM) of the HFC network.
Existing radio frequency over glass (RFoG) technologies can implement that a DOCSIS network is extended from a peripheral unit to a CM of a building user unit using an optical distribution network (ODN). An RFoG network can share an ODN with a passive optical network (PON), and uplink and downlink bandwidths (where the uplink bandwidth is 1610 nanometer (nm), and the downlink bandwidth is 1550 nm) provided by the RFoG network are compatible with uplink and downlink bandwidth (where the uplink bandwidth is 1310 nm, and the downlink bandwidth is 1490 nm) of the PON. A downlink channel of the RFoG network and that of an HFC network are identical and both use a broadcasting transmission service, but a difference lies in burst mode time division multiplexing (TDM) used by an optical network unit (ONU) of the RFoG network during transmission of an uplink signal, that is, an radio frequency over glass optical network unit (R-ONU) transmitting circuit automatically controls, by automatically detecting a level of a radio frequency signal, a laser on an uplink channel to be enabled and disabled, and transmits, in an optical fiber, a radio frequency signal by means of amplitude modulation and/or frequency modulation. It must be ensured that a cable modem termination system (CMTS) can perform uplink communication with one or more CMs that are located after only one R-ONU. If two or more R-ONUs that have a same wavelength or similar wavelengths simultaneously perform uplink transmission in an optical fiber, optical beat interference occurs, causing a decrease in a signal-to-noise ratio of an uplink signal, packet loss and the like, which seriously affect uplink communication.
For DOCSIS 3.1, both orthogonal frequency division multiple access (OFDMA) and single channel quadrature amplitude modulation (SC-QAM) technologies are used in the uplink. A difference between the OFDMA technology and the SC-QAM technology lies in uplink TDM in the uplink of the SC-QAM, multiple CMs simultaneously send an uplink signal in one OFDMA frame, and if in one OFDMA frame, multiple CMs are located after multiple R-ONUs that have a same wavelength or similar wavelengths, a conflict inevitably exists in the uplink of an RFoG system.